Advanced method for mitigating leakage signal in FMCW radar and radar system therefor

Abstract

A method for mitigating a leakage signal in an FMCW radar and a radar system thereof are disclosed. The method for mitigating the leakage signal in the radar system includes generating an in-phase signal and a quadrature signal for a beat signal, generating a complex signal using the in-phase signal and the quadrature signal, concentrating a phase noise of the leakage signal included in the complex signal on a stationary point, and mitigating the phase noise based on stationary point concentration (SPC) of the phase noise.

What is claimed is: 
     
       1. A method for mitigating a leakage signal in a radar system, the method comprising:
 transmitting at least one signal via a transmitter; 
 receiving at least one reflection via a receiver; 
 reducing the leakage signal between the transmitter and receiver, comprising the stepS of: 
 generating an in-phase signal and a quadrature signal for a beat signal; 
 generating a complex signal using the in-phase signal and the quadrature signal; 
 concentrating a phase noise of the leakage signal included in the complex signal on a stationary point; and 
 mitigating the phase noise based on stationary point concentration (SPC) of the phase noise; 
 wherein the step of concentrating includes extracting a first signal from the complex signal by performing DC removal and in-phase/quadrature imbalance correction for the complex signal; 
 obtaining a spectrum in the form of magnitude response after performing fast Fourier transform (FFT) accompanied with zero padding for the first signal and finding an index of the leakage signal using peak searching; 
 extracting a beat frequency value of the leakage signal based on the index of the leakage signal; 
 extracting a phase value of the leakage signal based on the index of the leakage signal; 
 generating a digital numerically controlled oscillator (NCO) based on the extracted beat frequency value and the extracted phase value; and 
 performing a down-conversion step by taking a complex conjugate of the digital NCO and multiplying the complex conjugate by the first signal to remove the extracted beat frequency value and the extracted phase value of the leakage signal. 
 
     
     
       2. The method of  claim 1 , wherein the concentrating step includes:
 concentrating the phase noise on the stationary point using an SPC technique by concentrating the phase noise of the leakage signal on a stationary point of a cosine function. 
 
     
     
       3. The method of  claim 1 , wherein the concentrating step includes:
 concentrating the phase noise of the leakage signal on the stationary point by performing sampling at a minimum sampling frequency according to the Nyquist sampling theorem, with regard to a maximum detection distance without the necessity of oversampling and strategic frequency planning. 
 
     
     
       4. A radar system for mitigating a leakage signal, the radar system comprising:
 a first means configured to generate an in-phase signal and a quadrature signal for a beat signal; 
 a second means configured to generate a complex signal using the in-phase signal and the quadrature signal and concentrate a phase noise of the leakage signal included in the complex signal on a stationary point; and 
 a third means configured to mitigate the phase noise based on stationary point concentration (SPC) of the phase noise; 
 wherein the second means (i) extracts a first signal from the complex signal by performing DC removal and in-phase/quadrature imbalance correction for the complex signal, (ii) obtains a spectrum in the form of magnitude response after performing fast Fourier transform (FFT) accompanied with zero padding for the first signal and finds an index of the leakage signal using peak searching, (iii) extracts a beat frequency value of the leakage signal based on the index of the leakage signal and extracts a phase value of the leakage signal based on the index of the leakage signal, (iv) generates a digital numerically controlled oscillator (NCO) based on the extracted beat frequency value of the leakage signal and the extracted phase value of the leakage signal, and (v) performs a down-conversion step by taking a complex conjugate of the digital NCO and multiplying the complex conjugate by the first signal to remove the extracted beat frequency value and the extracted phase value of the leakage signal. 
 
     
     
       5. The radar system of  claim 4 , wherein the second means concentrates the phase noise on the stationary point using an SPC technique by concentrating the phase noise of the leakage signal on a stationary point of a cosine function. 
     
     
       6. The radar system of  claim 4 , wherein the second means concentrates the phase noise of the leakage signal on the stationary point by performing sampling at a minimum sampling frequency according to the Nyquist sampling theorem, with regard to a maximum detection distance without the necessity of oversampling and strategic frequency planning. 
     
     
       7. A radar system for removing a beat frequency value and a phase value of a leakage signal, the radar system comprising:
 a transmit (TX) radio frequency (RF) stage; 
 a receive (RX) RF stage; 
 a TX intermediate frequency (IF) stage; 
 a mixer; 
 an RX IF stage; 
 first and second analog-to-digital converters (ADCs); and 
 a leakage signal attenuation stage, 
 wherein the first and second ADCs sample an in-phase signal and a quadrature signal for a beat signal output from the RX IF stage to a predetermined frequency, and 
 wherein the leakage signal attenuation stage generates a complex signal using the in-phase signal and the complex signal, extracts a first signal from the complex signal by performing DC removal and in-phase/quadrature imbalance correction for the complex signal, extracts a beat frequency value of the leakage signal and a phase value of the leakage signal, and performs a final down-conversion step of generating a digital numerically controlled oscillator (NCO), based on the extracted beat frequency value and the extracted phase value, and multiplying the digital NCO by the first signal. 
 
     
     
       8. The radar system of  claim 7 , wherein the leakage signal attenuation stage obtains a spectrum in the form of magnitude response after performing fast Fourier transform (FFT) accompanied with zero padding for the first signal and finds an index of the leakage signal using peak searching, extracts the beat frequency value of the leakage signal based on the index of the leakage signal and extracts the phase value of the leakage signal based on the index of the leakage signal, and performs a down-conversion step by taking a complex conjugate of the digital NCO and multiplying the complex conjugate by the first signal to remove the extracted beat frequency value and the extracted phase value of the leakage signal. 
     
     
       9. The radar system of  claim 7 , wherein the mixer provides the RX IF stage with an in-phase beat signal and a quadrature beat signal by including an in-phase mixer and a quadrature mixer and performing quadrature demodulation.